[1] For centuries, scientists have marveled at the durability of ancient Roman concrete, which has survived for two millennia in harsh marine environments. [2] In contrast, modern concrete structures often begin to degrade within a few decades. [3] Recently, researchers discovered that the secret to this longevity lies in 'lime clasts'—small, white mineral chunks found throughout the ancient material. [4] The researchers used high-resolution electron microscopes to analyze the samples in their campus laboratories. [5] Previously dismissed as evidence of poor mixing, these clasts actually provide a self-healing mechanism when water enters cracks in the concrete, reacting to block further damage.
The writer is considering deleting Sentence 4 from the passage. Should this sentence be kept or deleted?
- AKept, because it provides necessary context regarding the scientific methodology used to study the concrete.
- BKept, because it explains the physical mechanism that allows the lime clasts to heal cracks in the concrete.
- Deleted, because it interrupts the explanation of the concrete's durability with irrelevant details about laboratory equipment.Cevap
- DDeleted, because it repeats information about the discovery of the lime clasts that is already stated earlier in the paragraph.